In the second year of the granting period, it is the intent of the investigators to continue their studies on the environmental factors which may influence the synthesis and/or biological activity of prostaglandins derived from rheumatoid synovial tissue and articular cartilage. In addition, studies will continue on the urinary analysis of prostaglandins in patients with chondrosarcoma, as will prostaglandin synthetic capacity of chondrosarcoma and serum protaglandin metabolizing enzymes. These studies should provide interesting data on the significance of prostaglandins in inflammatory arthritis and in regulating growth of chondrosarcoma. Additional studies include the biochemical changes in cartilage matrix components induced by prostaglandins and the differential effect of various prostaglandins on isolated chondrocyte metabolism. BIBLIOGRAPHIC REFERENCES: Estrin, I., Lipiello, L. & Mankin, H.J.: Effect of Media Obtained from Epiphyseal Plate Organ Cultures on Articular Cartilage Metabolism. (Abst.) Trans. Ortho. Res. Soc. 2: 203, 1977. Lippiello, L., Mitrovic, D. & Mankin, H.J.: Effect of Prostaglandins on Metabolism of Isolated Chondrocytes. (Abst) Arth. & Rheum. 20: 125, 1977.